1. Field of the Invention
This invention relates to a self-inking stamp for performing an inking upstroke, comprising a base part, which is adapted to be placed on the surface to be stamped and comprising an ink pad, which is opposite to the bottom surface of the base part, a type plate carrier, which is disposed in the base part and adapted to be reciprocated between the ink pad and the bottom surface of the base part and to be inverted during each stroke, and an actuating member, which embraces the base part with two side legs, which are guided on the narrow side walls of the base part, and is adapted to be displaced against spring force toward the bottom surface of the base part and the free ends of the side legs of which are interconnected by a pivot, which extends through slots formed in the narrow side walls of the base part, wherein the type plate carrier is pivoted on said pivot, which is formed with laterally disposed longitudinal track grooves for receiving respective guide pins, constraining straps are provided between the type plate carrier and the narrow side walls of the base part, each of said straps is formed with a cam slot, through which said pivot extends, each of said straps carries one of said guide pins adjacent to the center of said cam slot, and said constraining straps are pivoted in the narrow side walls of the base part by pivot pins disposed above the associated cam slot.
2. Description of the Prior Art
Such self-inking stamps have been known in practice for a very long time. As the actuating member is displaced against spring force toward the bottom surface of the base part, the pivot for the type carrier, which pivot connects the free ends of the side legs of the actuating member, will move in the slots of the narrow side walls of the base part and also in the cam slots of the two constraining straps, which owing to the curved shape of the cam slots perform an oscillating pivotal motion. Because guide pins are carried by said straps adjacent to the center of the cam slots and extend into the laterally disposed longitudinal track grooves of the type plate carrier, which is pivoted on the pivot and is moved by said pivot to the bottom surface of the base part, that type plate carrier is also pivoted about the pivot so that the type plate, which in a position of a rest faced away from the bottom surface of the base part and was in contact with the ink pad, is inverted to a position in which it faces the surface to be stamped and is forced against said surface. As the actuating member is returned by spring action, the type plate carrier is also swung back through 180.degree. so that the type plate again contacts the ink pad.
In the prior art, each constraining strap constitutes a separate part, which can be mounted only with difficulty. Each strap must individually be inserted into the boxlike base part. This is complicated because the base part has an access opening only in its bottom and care must be taken that the pivot pin of each strap is received by the associated bearing hole in the narrow side wall of the base part. Even when the pivot pin has been received by the associated bearing hole, the strap carrying that pivot pin has not yet been fixed but must be urged from the inside against the narrow side wall until the type plate carrier has been inserted and now prevents a separation of the two straps from the narrow side walls. Moreover, the two constraining straps of a stamp cannot be interchanged but are associated with respective ones of the narrow side walls because otherwise the cam slots on both sides would be curved in mutually opposite senses. For this reason care must be taken during the assembling of a stamp that the constraining straps are properly selected and associated. As a result, the assembling of the self-inking stamp is a rather complicated operation.